Because the Arduino environment normally uses a very small subset of the language, neither are the best place for a beginner to start, nor are many of the other on-line tutorials. I’d still suggest you have both of those available for reference.
However, there is this: http://www.me.umn.edu/courses/me2011/arduino/arduinoGuide.pdf which does look to be a good starting place for a beginner. It does not go as far as classes and methods that are used here, though. For that, you need the Relisoft course.